There appear to be two
distinct subgroups within Group 8 that can be contrasted with the remaining
kits.One, which I will call the
"12" subgroup, is distinguished by a value of 12 for marker 22, and
consists of kits #126464, 287032, and 341274.Because the Group 8 standard has a value
of 15 for this marker, and there are no intermediate values (i.e., 13 or 14)
among the other kits, it seems likely that the change from a value of 15 to 12
occurred through a single mutation event.

The other, which I will call
the "11-17" subgroup, is distinguished by a pair of values: 11 for
marker 26, and 17 for marker 30.The kits are #57613, 263785, and 308906.The two mutations may have occurred
either as a single event, or as two events close together in time.

The remaining kits appear to
have no distinctive characteristics that allow groupings.Although three kits show a value of 35
for marker 34, they include two in the "11-17" subgroup, and one
outside that subgroup.Similarly,
five kits show a value of 39 for marker 35, but they include kits both inside
and outside the "12"and
"11-17" subgroups.It
seems likely that markers 34 and 35 independently mutated at several different
times for different kits.

Although the remaining kits (which
I will call the "remainder" group) cannot be said to form a subgroup,
they do have an interesting characteristic: They show smaller deviations from
the group standard than either of the two subgroups.If confined to ancestors with some form
of the surname, and at least 37 markers, they include kits #29401, 106142,
164685, 198726, and 355920.The
average deviation from the group standard is 1.80 markers for these five
kits.That contrasts with an average
deviation of 2.33 markers for the "12" subgroup, and 3.67 markers for
the "11-17" subgroup.

What the average deviations
suggest is that members of the "remainder" group split off the
ancestral line at a later date than either of the subgroups, with the "12"
subgroup having split off at an intermediate time, and the "11-17"
subgroup at the earliest time.These times can be estimated, first by the number of generations.

1. "12" subgroup:
This subgroup deviates by an average of 3.67 out of 37 markers from the
"remainder" group.Assuming
the "remainder" group split off the ancestral line at a later date,
that average can be converted to generations using the calculator located at http://dna-project.clan-donald-usa.org/tmrca.htm.The calculator indicates that the "12"
subgroup split has an expected value of 13 generations in the past.

2. "11-17"
subgroup: This subgroup deviates by an average of 4.67 out of 37 markers from
the "remainder" group.The calculator shows that the split has an expected value of 16
generations in the past.However, a
second estimate can also be made using the average difference from the
"12" subgroup since it more recently split from the ancestral line.That average is 5.56 markers, with an
expected value of 18 generations.Thus from the two comparisons, the overall expected value can be placed
in the middle at 17 generations.

These generation estimates
can be converted to years using an average value of 31 years per generation
(see the calculator page cited above).

1. "12" subgroup:
13 generations corresponds to 13 X 31 = 403 years.Estimating the average birthyear of the
"12" subgroup testees at about 1960 places the split from the
ancestral line at about the year 1557.

2. "11-17"
subgroup: 17 generations corresponds to 17 X 31 = 527 years.Under the same birthyear assumption,
this places the split at about the year 1433.

About all that can be said
about the "remainder" group is that its members generally split off
their common ancestral line more recently than either of the two subgroups,
i.e., after 1557.In other words
they share ancestry more recently than that (although note the caveats
below).But because it is not a
cohesive subgroup, the length of their shared ancestry likely depends on which
individuals are compared to one another.

Caveats

These conclusions come with
some caveats.The most important is
that the generational estimates are estimates only, and can be off to a
substantial degree.While the
strength of the subgroup approach is that every subgroup member provides an
independent generational estimate, reducing the amount of uncertainty, with
only three members in each subgroup the beneficial effect is small at the
moment.My best calculation is that
currently, the 95% confidence intervals for each subgroup include a little less
than 7 generations in either direction.In other words, for the "12" group, while the expected number
of generations since the split is 13, it could actually be anywhere from 6 to
20.For the "11-17" group
the expected number is 17 but could be anywhere from 10 to 24.

Another source of uncertainty
comes from the conversion of generations to years.Although 31 years per generation may be
the mean, this value obviously can vary quite a bit.

The answer to these caveats
is to add more subgroup members.Increasing sample sizes will reduce the size of the 95% confidence
intervals, and should bring the years per generation increasingly into line
with the 31 year average.Hopefully
the identification of Group 8 with the Kelburn Boyle family will encourage an
increased rate of kit submission, and lead to larger subgroups.It is also possible that new subgroups
will be discovered.

Finally, keep in mind that
these are my personal conclusions only.Please don't attribute them to FTDNA.